The purpose of this study is to determine the extent to which low dose oral contraceptives will affect spontaneous and stimulated (exercise) 24-hour GH secretions in young women. We will also examine the effect that estrogen has on body composition, specifically total body percent fat and regional distribution of body fat. Body composition will be determined using a 4 compartment model, regional fat distribution by CT and GH secretion by frequent blood sampling combined with ultrasensitive assay techniques. A total of 6 women have completed protocol and 5 have dropped out of study; will recruit 6 additional subjects.